Hur fattar samhället beslut när forskarna är oeniga? Martin Peterson m.peterson@tue.nl www.martinpeterson.org
Oenighet om vad? 1.Hårda vetenskapliga fakta? ( X observerades vid tid t ) 1.Den vetenskapliga tolkningen av hårda vetenskapliga fakta? ( X orsakar Y ) 1. Hur man bör översätta vetenskapliga fynd, och tolkningar av dem, till påståenden som vanligt folk kan förstå. ( X är säkert. ) 4. Moraliska och politiska värden. ( Vi bör göra X )
. Oenighet som förefaller vara vetenskaplig är ibland orsakad av moralisk oenighet. Oenighet som förefaller vara moralisk är ibland orsakad av vetenskaplig oenighet.
Under vilka omständigheter är enighet möjlig?
Betydelsen av förtroende
Betydelsen av förtroende
Debatten om kärnavfall?
Betydelsen av konstant och stabil information
Betydelsen av konstant och stabil information
Är simuleringarna robusta?
Del II: Beslutsfattande under vetenskaplig oenighet.
Försiktighetsprincipen Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation. (UNCED) When an activity raises threats of harm to the environment or human health, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. (Wingspread Conference)
Vad slags princip är FP? En legal princip En normativ princip En epistemisk princip
. Normativa tolkningar av FP: Vad bör vi göra? Epistemiska tolkningar av PP: Vad bör vi tro? - Omvänd bevisbörda? - Falska positiva/negativa fel - Oeniga experter
Two claims FP är inte ett rimligt påstpende om vad vi bör göra. FP kan vara ett ett rimligt påstående om vad vi bör tro.
Tre typer av beslutsproblem State 1 State 2 Act 1 (-7, 0.8) (+12; 0.2) Act 2 (-48, 0.8) (+99; 0.2) State 1 State 2 Act 1 (bad) (very good) Act 2 (good) (good) Act 1 Act 2 State 1 State 2 (bad, probable) (good, probable) (bad, improbable) (good, improbable) probable, improbable = Qualitative likelihood. [Let V>W] good,bad = Qualitative desirability. [Let a > b]
Omöjlighetsteorem no. 1 PP_min: If one act is more likely to give rise to a fatal outcome than another, then the latter should be preferred to the former; and if the two acts are equally likely to give rise to a fatal outcome, then they should be equi-preferred. Act 1 a f g Act 2 a g f
Ytterligare axiom Axiom (D): If one act yields at least as good outcomes as another under all possible states of the world, then the latter is not preferred to the former. Axiom (C): If the relative likelihood of a bad outcome decreases in relation to a strictly better outcome, then the new act is strictly preferred to the original one. Axiom (O): Preferences between acts are complete, antisymmetric, and transitive.
The epistemic interpretation Consider: In a precautionary appraisal of risk, it is more desirable from an epistemic point of view to avoid false negative errors compared to false positive ones. False positive error: = False alarm! You incorrectly think there is a correlation between some variable where none really exists. False negative error: You fail to discover a correlation between some variables.
Two objections Can we choose what to believe? What about truth? Why care about pragmatic reasons for beliefs? ( I m the best chess player in the world )
Another objection to the epistemic version of PP: You live in the jungle. Tigers are yellow and black. Everything eatable in the jungle is also yellow (Bananas) To protect yourself against tigers you build a device that detects and warns for everything that is yellow. The detector is very sensitive Many false positives --------------------------------------------------------- Good news: Because of the detector you will not be killed by a tiger. Bad news: You will starve to death, because you will never find anything to eat. ----------------------------------------------------------- Conclusion: It is far from clear that it is in general better to prefer false positives over false negatives.